The purpose is to discover whether the market mechanism, in the process of its continuous reallocation of workers and their families among SMSA'S, strikes the proper balance between (a) moving them to locations where they will contribute most to the nation's output, and (b) moving them in accord with their own preferences. In an NICHD-supported project conducted during 1973-74, the principal investigator found that the largest 11 metropolitan labor markets, because of the net economic advantages associated with bigness, are the most advantageous locations in terms of national output for workers on the move. Yet net inmigration rates for these labor markets are below the national average. We must therefore learn whether worker preferences to locate elsewhere is what constrains migration to the larger metropolitan aras, or whether labor market immobility and imperfections exist that need to be addressed by government policy. The 1973-74 research findings document the demand side of the inter-urban labor market. Not a great deal is known about the supply side however. We propose to address this question by estimating an inter-urban labor supply function -- using both cross-sectional and survey data. Only with both the supply and demand functions in hand can we know whether the geographic labor market functions efficiently.